The present invention relates, in general, to a single turn ferrite rod antenna and method. More particularly, the present invention relates to an antenna and method resulting in a high "Q", high sensitivity antenna suitable for use in conjunction with miniaturized receivers.
Requirements for decreased size of paging and radio receiver packages have necessitated simplification and down-sizing of antenna elements to meet manufacturing and size constraints. However, the antenna must, nevertheless, provide a sufficiently high "Q" (low loss) while simultaneously exhibiting sufficient radiated signal sensitivity. Existing technologies have been unsatisfactory in meeting these constraints.
U.S. Pat. No. 3,267,478 issued to Schiefer on Aug. 16, 1966, and U.S. Pat. No. 3,594,805 issued to Chardin on Jul. 20, 1971 describe tunable ferromagnetic rod loop antennas comprising a cylindrical core surrounded by a sleeve of electrically conductive material. A gap was provided running the entire length of the sleeve and included a plurality of capacitors distributed and spaced equidistantly throughout the length. A coupling winding surrounded at least a portion of the core of the Schiefer antenna and included a pair of wires for coupling the antenna assembly to the receiver. A second split sleeve was positioned over the first sleeve of the Chardin antenna to adjust the inductance of the assembly by masking portions of a second longitudinal slot on the first sleeve. Neither antenna provided a means for readily mounting the antenna to a printed circuit board. As a consequence, such an antenna is not suitable for use with today's advanced manufacturing processes, such as surface mount technologies and automated assembly techniques.
U.S. Pat. No. 4,814,782 issued to Chai Mar. 21, 1989 and assigned to the assignee of the present invention, described an antenna having a structure somewhat similar to that described by Schiefer, but having provision for mounting the antenna to a printed circuit board. In particular, the sleeve further included integral mounting tabs for securing the antenna assembly to the printed circuit board while establishing electrical connection to the antenna without the use of wire leads. Such an antenna as described by Chai provided a significant improvement over the prior art in both construction and mounting. However, because the mechanical connections and the electrical connections were in common, reduced antenna performance could occur during extreme shock and/or drop conditions due to large stresses being placed on the mounting tabs.
It would therefore be highly desirable to provide an expedient structure for and method of mounting and electrically connecting the antenna to a printed circuit board which would provide improved mechanical mounting of the ferrite core loop antenna to withstand even more extreme environmental influences, such as higher mechanical shock levels, without the use of extraneous mounting hardware.